Multi component transport pallet

ABSTRACT

A transport pallet made from plastic material, comprising a cover plate ( 1 ) forming a support surface ( 2 ) for goods to be received, and a base element ( 3 ) and support elements ( 5 ) between the cover plate ( 1 ) and the base element ( 3 ), wherein the support elements ( 5 ) are formed separately or as a part of the cover plate ( 1 ) and/or the base element ( 3 ) and connect the cover plate and the base element with one another at a distance from one another or form openings between one another for an engagement of lifting devices, in particular for an engagement of fork prongs of a forklift, characterized in that the cover plate ( 1 ) and the base element ( 3 ) are connected with one another by closure elements ( 11 ) which are respectively formed with a rated breaking point ( 25 ).

The invention relates to a transport pallet made from plastic material according to the preamble of patent claim one.

Transport pallets made from plastic material are generally used for transporting stackable goods and similar. The transport pallets can be provided in different sizes wherein however the dimensions for so-called euro pallets are predetermined due to standardization. This is provided for reasons of simplifying transportation so that transport pallets from different vendors are compatible without any problems with other pallets.

Transport pallets made from plastic material are typically provided in two components and include a cover plate which forms the actual support surface for goods to be received and a base element which forms a standing surface for the transport pallet. The cover plate and the base element are connected with one another by plural support elements over a circumference but also in center portions of the pallet wherein the support elements are either configured separately and/or configured at the cover plate or at the base element. In order to form the pallet the individual elements of the pallet, thus the cover plate and the base bar are permanently connected with the support elements through welding or gluing. However, there are also pallets in which the cover plate is firmly interlocked with the base bar through snap locking elements (DE 10 2006 027 451 A1) in order to provide an interconnection between the cover plate and the base element for forming the transport pallet. Interlocking connections of this type which are typically formed from plural engagement lugs and complementary engagement recess have a certain amount of flexibility due to tolerances which to a certain extent helps to avoid damaging the pallet in the portion of the support bases with respect to lateral collision forces as they can occur for example when the pallet is handled with a forklift. The engagement lugs can tear under excessive loads which can lead to a destruction of the support elements which in the simplest case requires a the reinstallation of the support base but which can also lead to damages of the engagement members configured with the support lugs, so that complex repair work is required.

Eventually also pallets are known in which the cover plate is firmly connected with the base bar through bayonet bolts (DE 10 2008 047 856 A1) which provides a stable interconnection. Under excessive loads when handling the pallets with a forklift with a heavy load on the pallet the pallet can be damaged in particular in the portion of the support members.

Handling the pallets, in particular the pallets that a loaded with goods, is typically performed with forklifts or similar lifting devices. Thus, the pallets are circumferentially provided with a respective openings for engagement of the forklift tongs or other engagement elements, wherein typically the adjacent support elements form the engagement openings for the forklift tongues and similar between one another.

Increasingly special lifting carts are used for transporting the pallets wherein these lifting carts can also be forklifts which, however, are provided with an additional elevation adjustable mast lifting element. These lifting carts include a wheel arm lifting element in a lower portion which wheel arm lifting element is separate from the mast lifting element arranged there above. These lifting carts improve stacking work and facilitate for example removing half pallets from euro pallets. Lifting carts of this type with separate wheel arm lift and mast lift are produced for example by the Jungheinrich Company, however they are also available from other vendors.

During incorrect use of forklifts of this type, however, it can occur that the cover plate is preloaded relative to the base element during engagement of the wheel arm lifting element in the engagement opening and also of the mast lifting element in the engagement opening while moving the lifting elements apart, which leads to a deformation of the pallet and even to a separation of the cover plate from the base element through tearing in the portion of the support elements.

In the field of pallets with support bases and with skids arranged at the support bases it is already known to provide rated breaking points in order to prevent damages to the pallet during handling with a forklift. This is achieved in that the support bases are configured sleeve shaped and by using an engagement element that is advantageously glued together with the cover plate and arranged at an upper end of the support base which upper end is oriented towards the cover plate of the pallet wherein the engagement element engages respective engagement recesses at the inner wall of the sleeve shaped support base with laterally extending engagement lugs. Thus, a certain flexibility of the support bases with respect to lateral collision forces shall be achieved, wherein the interlocked connection can also act as a rated breaking point in case of extreme collisions. This means that the engagement element can disengage from the support bases, so that a new support base can be inserted as required. This means that the interlocking can be levered out when large forces occur, for example when incorrect handling is performed by a forklift, so that the interlocking is disengaged.

It is furthermore also known for pallets configured from individual components to use bayonet bolts as connection members, thus for example for attaching replaceable supports skids at support bases according to DE 10 2008 047 856A1.

Thus, it is an object of the invention to provide a transport pallet which is configured simple and robust and which avoids deformations and distractions safely even when lifting cart is used incorrectly.

This object is achieved according to the invention by the features in the characterizing portion of claim 1, wherein advantageous embodiments of the invention are characterized by the features included in the dependent claims.

According to the invention the cover plate is connected with the base element by separate closure elements, in particular closure bolts wherein each closure element is advantageously arranged in a support element and provided with a rated breaking point that is configured as a tension element. When forklifts, in particular forklifts with two lifting elements that can be moved relative to one another are used incorrectly a tear off of the closure element and their destruction would occur during a respective preloading of the components of the pallet, thus the cover plate, base elements and the support elements, without the remaining elements of the pallet being damaged. Thus, the pallet elements are reusable in that the cover plate is connected with the base plate through new closure elements.

Advantageously each closure element is configured as a tension element which firmly connects the cover plate and the base element with one another through tensioning. In particular the closure element is configured as a bayonet closure element according to claim 4 which yields a simple attachment of the pallet elements and only the bayonet bolts need to be inserted into the respective receivers and rotated, so that the cover plate and the base plate are clamped together so that a stable interconnection of the pallet is achieved.

Thus it is advantageous that each of the support elements which hold the base plate and the cover plate at a distance from one another and connects them with one another is configured with at least one closure element.

As an alternative to the bayonet closure the closure element can also be configured as a bolt with a screw thread which is insertable into a respective screw thread opening at the base plate or the base bar.

Advantageously the closure bolts are inserted from below, this means from a bottom side of the base bar in upward direction. Advantageously the bolt is formed here with an expansion so that a bolt section is formed that has a larger diameter than the bolt diameter, wherein the bayonet closure or the screw closure is provided at the opposite bolt end. This yields a respective stop when actuating the bayonet closure or the screw thread in order to provide a clamping effect between the elements in order to form the pallet.

Advantageously the closure elements are made from plastic material, thus advantageously bolt shaped, wherein the bolts in turn are advantageously configured hollow.

The rated breakpoint can be for example formed in a simple manner through a circumferential groove, in particular a V-shaped notch. In particular the depth of the groove and the material weakening of the closure element caused thereby or of the wall thickness of the closure element advantageously configured as a hollow bolt allows to predetermine the sensibility of the rated breakpoint with simple measures, this means it can be determined above which introduced force the rated breaking of the closure element occurs. However forming the rated breakpoint as a groove or notch is not mandatory, rather the rated breakpoint can also be configured differently, thus in that openings or similar perforations or material weakening's are provided over the circumference.

Engagement elements for a rotating tool are advantageously provided at ends of the bolt that are opposite to the bayonet closure or the screw thread so that the bolts can be screwed in in a simple manner with a suitable tool. Thus, it is advantageous that the expanded bolt section includes an inner wall and an outer wall which define an annular cavity between one another, wherein offset ribs within radial bars are provided within the annular cavity, wherein the ribs connect the inner wall with the outer wall and form respective stop surfaces for engagement of the rotating tool for rotating the bolt in order to provide the preload. Subsequently an embodiment of the invention is described with reference to drawing figures, wherein:

FIG. 1 illustrates a corner element of a transport pallet in an exploded view with a disengaged closure element;

FIG. 2 illustrates a view through a portion of the pallet illustrated in FIG. 1 in order to better illustrate the closure element in its closed position;

FIG. 3 illustrates a sectional view through a portion of the transport pallet for illustrating the support element and the closure element in its tension position;

FIG. 4 illustrates an enlarged view of the bayonet closure element with two screw thread shaped sections arranged opposite to one another; and

FIG. 5 illustrates an enlarged view of the head element of another embodiment of a bayonet bolt with its lower expanded headpiece.

FIG. 1 illustrates a transport pallet in an exploded view thus only a corner section of the plastic transport pallet which is produced in a known manner from plastic material through injection molding, extruding or similar. Thus numeral 1 designates the cover plate which forms the support surface 2 of the transport pallet with its upper main surface. Below the cover plate 1 there is the base element 3 of the pallet which is formed herein by skids 4 that extend in parallel and perpendicular to one another, wherein the skids form the contact surfaces for the base element 3.

The upper cover plate 1 and the base element 3 arranged thereunder are arranged at a distance from one another thus through support elements 5 which can be provided in different configurations. In the illustrated embodiment the support elements 5 are formed by support element sections 5 a integrally molded at a bottom side of the cover plate 1, protruding in downward direction and circumferentially configured, through upward oriented support element sections 5 b integrally molded at the topside of the base element 3, wherein the support element sections 5 b are also circumferentially configured, and by a support sleeve 5 c placed there above one an outside. The lower support element section 5 b includes an inner wall 6 and an outer wall 7 that are offset from one another and in an assembled condition the sleeve 5 c contacts the outer wall 7. The support element section 5 a integrally molded at the upper cover plate 1 contacts the inner wall 6 and the upper face 8 of the sleeve 5 and contacts an upper shoulder 9 of the cover plate 1 so that a stable support interconnection is provided.

FIG. 1 also illustrates a closure element 11 which is formed herein by a bolt 12 which has an annular expansion at its lower free end and a bolt section 13 with a larger diameter than the bolt 12. At the opposite end of the furthermore hollow configured bolt that is made from plastic material there is a bayonet closure element 14 which is formed herein by two opposite screw thread sections 15 that extend over a partial circumference of the bolt and protrude in an outward direction, wherein, however, only one screw thread section 15 is illustrated in FIG. 1. The non-illustrated screw thread section is exactly on the opposite side of the closure bolt which is not visible in this figure illustration.

FIG. 2 illustrates the bolt shaped closure element 11 in assembled condition. For this purpose the bolt 12 is inserted from a bottom side of the base element 3 into the support base through which it reaches completely which, however, is not mandatory. The bolt according to FIG. 2 is inserted into a sleeve 17 formed in an interior of the support element section 5 b which sleeve is connected according to FIG. 2 through a radial bars 18 with the inner wall 6 of the support element section 5 b. The bolt extends through the sleeve 5 c in upward direction into a sleeve shaped receiving opening 19 of the upper cover plate or of the support element section 5 a, wherein the opening is also evident at the support surface 2 of the cover plate 1 in FIG. 1. Shoulders 21 that are complementary to the bayonet closure element 11 are provided in the opening 19, wherein the shoulders only extend over a partial circumference of the opening 19 and form the actual bayonet closure together with the bayonet closure element 11 or the two screw thread sections 15 described herein.

Since the screw sections 15 of the bayonet closure element 14 and also the opposite shoulders 21 interacting therewith are arranged at such distance from one another so that the bolt with the bayonet closure element 14 can be run through, the bayonet closure element only has to be the rotated after inserting the closure bolt 12, so that the bayonet surfaces are preloaded relative to one another.

Since the bolt section 13 configured at a head of the closure bolt 12 furthermore contacts an opposite shoulder 23 in an opening 24 of the base element 3 a corresponding preload is achieved with increasing rotation of the bolt 12 so that a firm interconnection of the upper cover plate 1 with the lower base element 3 is provided.

As evident from the figures the hollow configured bolt 12 is configured with a rated breakpoint 25 that can be configured in a suitable manner, thus through a V-shaped groove shaped circumferential notch. In particular through the depth of the indentation and resulting material weakening of the bayonet bolt the braking force is predetermined at the rated breakpoint so that a respective setting is feasible beyond which force between cover plate and base element the predetermined rated fracture occurs. According to FIGS. 2 and 3 the rated breakpoint is advantageously configured at an upper end of the bolt 12, in particular at the cover plate or slightly below the bayonet element 15.

In the illustrated embodiment each support element 5 includes at least one receiver for a bolt shaped closure element 11. Optionally also two receivers can be provided as illustrated in FIG. 1 for the corner side support element 5.

After inserting the bolt 12 from a bottom side of the base bar 3 into the respective receiver in the respective support element and after the respective rotation of the bolt preloading is performed through the bayonet closure so that the cover plate 1 is firmly connected with the base element 3 to form the pallet. Since at least one closure bolt 12 is provided for each support element or each support base an interconnection of the pallet is provided that is stable over the entire circumference wherein, however, excessive load, for example during incorrect forklift actuation, in particular when using a forklift with a wheel arm lift and a mast, lift damaging the cover plate, the base bar 3 and the support elements 5 is safely avoided since the bolts at the rated breakpoint tear before these components are deformed. Thus, the components of the pallet can be reassembled again to form the transport pallet without further complexity by inserting respective closure bolts 12.

In an alternative embodiment which, however, is not illustrated herein the bolt 12 instead of being provided with a bayonet closure at its upper end, is provided with a screw thread and can be screwed into a respective through screw thread opening of the cover plate 1. Also this preloads the cover plate 1 and the base element 3 relative to one another. When there is an excessive load and a fracture of a bolt at the rated breakpoint provided for this purpose the bolt can be unthreaded and the interconnection of the pallet can be provided through another screw bolt.

The expanded bolt section 13 as apparent from FIGS. 2 and 3 is provided with an inner wall and an outer wall which form an annular cavity 27 between one another. In the annular cavity 27 radial bars can be arranged at a distance from one another, thus in particular formed as ribs which extend from an inner wall to an outer wall and can be used as a contact surface for a suitable turning tool, so that the bolt can be threaded in or threaded out with a tool.

FIG. 4 illustrates the upper end of the bayonet closure element 11 interacting with the upper cover plate 1. Two opposite sections 15 with screw threads are clearly visible at an out the circumference of the bolt 12, wherein the sections are configured with a respective pitch and interact with shoulders 21 configured at the cover plate 1 so that a rotating the bolt 12 in closing direction preloads the screw thread shaped protrusions 15 with the shoulders so that the cover plate 1 is interlocked with the base element 3. When the bolt 12 is rotated in opposite direction the unlocking is performed.

However, in order to lock the belt 12 itself in its closed position a locking device generally designated as 30 according to FIG. 5 is provided. In the embodiment illustrated in FIG. 5 the locking device is configured at the head end of the closure element 11. Thus, locking bars 33 are provided at the face shoulder 31 of the expanded head element 32 of the closure element 11 and distributed over the circumference, wherein the locking bars 33 interact with a teething 34 that is configured at a pallet, wherein the teething is configured at a sleeve element 35 of the base element or of the base bar 3, wherein the sleeve element 35 receives the bolt 12 of the closure element 11. The locking bars and the teething are thus configured so that rotating the closure element 11 into the closed position in order to lock the cover plate with the base element or the base bar advantageously automatically provides a locking acting against the closing movement due to the engagement of the locking bars 33 in the teething 34. This has the consequence that closing the bayonet bolt provides the interlocking between the cover plate and the base element or the base bar 3; however the bayonet closure is blocked in a reverse direction and cannot be disengage independently any more.

In the illustrated embodiment locking bars 33 are provided for this purpose with a slanted flank 36 and the teething 34 includes a locking shoulder 37 distributed over the circumference and advantageously oriented radially inward, wherein an additional slanted surface 38 adjoins the locking shoulder 37. During the closing movement the slanted surface 36 of the locking bar moves over the slanted surface 38 of the teething, whereas an opening of the bayonet closure is prevented in opposite direction in that the bar surface at each bar 33 comes in contact with a locking shoulder 37 of the teething 34 and thus a rotation in unlocking direction for opening the bayonet closure is blocked and prevented. Instead of the illustrated embodiment other embodiments are certainly feasible. For example one locking bar would already suffice, however plural locking bars distributed over the circumference, in particular four locking bars like in the illustrated embodiment are useful. Alternatively also an escapement type of ratchet mechanism can be used. 

1. A transport pallet made from plastic material, comprising a cover plate (1) forming a support surface (2) for goods to be received, and a base element (3) and support elements (5) between the cover plate (1) and the base element (3), wherein the support elements (5) are formed separately or as a part of the cover plate (1) and/or the base element (3) and connect the cover plate and the base element with one another at a distance from one another or form openings between one another for an engagement of lifting devices, in particular for an engagement of fork prongs of a forklift, characterized in that the cover plate (1) and the base element (3) are connected with one another by closure bolts (11) which are respectively formed with a rated breaking point (25), at least one respective closure bolt (12) is arranged in a respective support element (5), and that the closure bolt (11) is configured as a tension element which connects the cover plate (1) and the base element (3) with one another through preloading.
 2. The pallet according to claim 1, characterized in that the closure bolt (11) is advantageously configured hollow as a bayonet bolt (12) with bayonet shaped engagement members (14) or configured as a screw bolt.
 3. The pallet according to claim 1, characterized in that the rated breakpoint (25) is advantageously configured at the closure bolt (12) proximal to or in a portion of the cover plate (1).
 4. The pallet according to one of the preceding claims, characterized in that the rated breakpoint (25) is formed by a groove, in particular a V-shaped groove or a notch which is advantageously provided at an outer circumference of the bolt (12).
 5. The pallet according to claim 4, characterized in that the groove or the notch extends over an entire circumference of the closure element (11).
 6. The pallet according to one of the preceding claims, characterized in that the closure element (11) is configured hollow.
 7. The pallet according to one of the preceding claims, characterized in that the closure element (11) is made from plastic material.
 8. The pallet according to one of the preceding claims characterized in that the closure bolt (11) is configured at one end with a bayonet closure element (14), this means it includes at least one screw thread shaped section (15), advantageously two or more such screw thread sections (15) distributed over the circumference of the bolt, and wherein the bolt is expanded at its other end (13), wherein the bayonet closure element (14) interacts with at least one complementary opposites surface (21) at the cover plate (1) or the base element (3) for forming a bayonet closure and the opposite expanded end (13) of the bolt contacts a contact shoulder (23) of the base element (3) or of the cover plate (1), so that closing the bayonet closure by rotating the bolt firmly clamps the cover plate (1) to the base element (3).
 9. The pallet according to one of the claims 1 through 7, characterized in that the closure bolt (12) has a screw thread at one end and its other end (13) is expanded, and a complementary screw opening for the screw thread at the bolt (12) is provided at the cover plate (1) or at the base element (3) and the opposite expanded end (13) of the bolt contacts a contact shoulder (23) of the base element (3) or of the cover plate (1) so that screwing in the threaded bolt (12) firmly clamps the cover plate (1) at the base element (3).
 10. The pallet according to claim 8 or 9, characterized in that the closure bolts (12) are provided with a rated breakpoint (25) between the expansion (13) and the bayonet closure element (14) or the screw thread.
 11. The pallet according to one of the claims 8 through 10, characterized in that the closure bolt (12) includes an expansion (13) configured as a bolt section with an enlarged diameter which expansion is configured as an engagement element for a rotating tool.
 12. The pallet according to claim 11 characterized in that the engagement element is configured with one of plural radial ribs for an engagement of a rotating tool.
 13. The pallet according to one of the preceding claims, characterized in that the closure bolt (12) is provided with a fixation lock (30) that is advantageously self acting and operates against a locking or closure movement of the closure bolt (12).
 14. The pallet according to claim 13, characterized in that the fixation lock includes at least one locking bar (33) provided at the bayonet bolt, wherein the locking bar cooperates with a teething (34) provided at the pallet.
 15. The pallet according to claim 14, characterized in that at least one advantageously plural, in particular advantageously four locking bars (33) are provided that are distributed over the circumference of the bayonet bolt, wherein the locking bars are advantageously provided at an annular face shoulder (31) of the head element (32) of the closure element (11) and each locking bar (33) has a slanted ramp surface (36) and the teething is provided with a plurality of looking shoulders (37) and slanted flanks (38), so that the at least one locking bar (33) engages the at least one locking shoulder (32) during a rotation of the closure element (11) in the sense of unlocking the bayonet closure so that a disengagement of the closure bolt (12) is blocked. 